Happy birthday: 1,400% more bacteria lands on cakes when you blow out candles

Birthday celebrations. Who doesn’t love them? We at Neogen celebrated our 35th birthday as a company this year, and it’s been an exciting year so far.

Recently, however, there’s been some bad press surrounding birthday parties, coming along with an important food safety tip we and others should keep in mind.

We’ll put it shortly: birthday candles. When you blow out the gentle, warmly glowing flames that flicker above that chocolate frosting, there’s an unfortunate unintended consequence. Any bacteria from saliva carried on your breath will, unfortunately, land atop that glorious birthday cake.

A recent study took a look at exactly how much bacteria lands on cake after the candles are blown out. The research showed that compared with cakes without blown-out candles, blown-out-candle cakes had on average 1,400% more bacteria resting on the surface. We’ll let that number sink in.

You may be relieved to find out that no birthday cakes were harmed during the course of this experiment: researchers made fake cakes out of icing, tin foil and candles. They then conducted a very important step, the eating of pizza, and then blew out the candles on the imitation cakes. (The pizza was so that researchers would have a bacteria-growing environment in their mouths, just as real partygoers might.)

Icing samples were collected and tested with a nutrient agar meant to cultivate bacteria, growing their populations to detectable levels. This was when the team found bacteria colonies from candle samples to be much more prevalent than they were in non-candle samples.

So is birthday candle-blowing likely to infect every guest with a deadly disease, causing your next birthday party to end in tragedy? Probably not, or we’d all be dead by now. Is it kind of gross? You bet.